title: Kramers-Kronig analysis on the real refractive index of porous media in the terahertz spectral range.
abstract: We present a terahertz time-domain experimental technique for the detection of scattering from porous media. The method for detection of the scattering enables one to make a decision when Fresnel or Kramers-Kronig (K-K) analysis can be applied for a porous medium. In this study the real refractive index of a tablet is calculated using the conventional K-K dispersion relation and also using a singly subtractive K-K relation, which are applied to the extinction coefficient obtained from the Beer-Lambert law. The advantage of the K-K analysis is that one gets estimates both for absolute refractive index and also dispersion of the porous tablet, whereas Fresnel analysis provides only the absolute value of the index.
authors.affiliation: Department of Physics and Mathematics, University of Eastern Finland, Joensuu, Finland. pertti.silfsten@uef.fi
authors.forename: Pertti
authors.initials: P
authors.lastname: Silfsten
authors.forename: Ville
authors.initials: V
authors.lastname: Kontturi
authors.forename: Tuomas
authors.initials: T
authors.lastname: Ervasti
authors.forename: Jarkko
authors.initials: J
authors.lastname: Ketolainen
authors.forename: Kai-Erik
authors.initials: KE
authors.lastname: Peiponen
mesh_terms: D016062:Porosity; D012542:Scattering, Radiation; D055068:Terahertz Spectroscopy / Q000379:methods*